In the field of valve actuators, single-piston actuating apparatuses are well known. Usually, single-piston apparatuses do not have continuous profiles because the fixing of the various components does not allow it. In these cases, the control electric valve of the actuator is only close to the actuator and some pneumatic connections are required to drive the actuator.
It is also well known that the most sophisticated versions of single-piston actuators use an electric valve of the “namur” type (with no pneumatic fittings), normally fixed to the rear head of the actuator or on the bottom of the actuator.
However, also in such a case, an outer pneumatic connection is required to send compressed air to the front head of the actuator.
Moreover, the device for detecting the position of the shaft for opening/closing the valve is usually inserted in a plastic box added to the actuator.
Moreover, known solutions integrate in the actuator a niche for the position control or an actuator coupling system, but both of them are never present in a single-piston monoblock system.
Moreover, even more advanced solutions available on the market, in which the compressed air ducts are integrated in the cylinder casing, have the drawback that the control electric valve protrudes with respect to the overall shape of the apparatus, and is therefore subject to possible breakage and to the hazardous entrance of dust, which can even seriously damage the electric valve and the actuator operation.
Furthermore, well-known problems in the apparatuses currently available on the market are:                stagnation of dust on the pneumatic actuators;        incorrect use due to the appearance of connection errors;        breakage of the boxes containing the position detectors.        